Fixed to #include correct 32-bit headers; Refreshed libc/kernel headers

This patch fixes an issue where 64-bit hreaders are incorrectly included
in kernel headers.  For example, file "libc/kernel/arch-x86/asm/io.h"
incorreclty includes "io_64.h" (missing, BTW) instead of "io_32.h".

The reason is because CONFIG_X86_32 isn't considered pre-defined in
"kernel_default_arch_macros" for x86, and clean_header.py doesn't
look at it at all anyway (ie. __i386__ is also ignored, but it's
okay since x86 cross compiler defines it back)

Fixed 2 tools/*py, README.TXT, and refreshed libc/kernel headers

Change-Id: Iac834cc8b3548f055d3f2a214af36072dd679fe8

libc/kernel/tools/clean_header.py

@@ -62,8 +62,11 @@ def  cleanupFile( path, original_path):
         sys.stderr.write( "error: can't parse '%s'" % path )
         sys.exit(1)
 
+    macros = kernel_known_macros.copy()
+    if arch and arch in kernel_default_arch_macros:
+        macros.update(kernel_default_arch_macros[arch])
 
-    blocks.optimizeMacros( kernel_known_macros )
+    blocks.optimizeMacros( macros )
     blocks.optimizeIf01()
     blocks.removeVarsAndFuncs( statics )
     blocks.replaceTokens( kernel_token_replacements )